Patent application title: GLASS FOR SCATTERING LAYER OF ORGANIC LED ELEMENT, LAMINATED SUBSTRATE FOR ORGANIC LED ELEMENT AND METHOD OF MANUFACTURING THE SAME, AND ORGANIC LED ELEMENT AND METHOD OF MANUFACTURING THE SAME

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Abstract:

Glass for a scattering layer of an organic LED includes, as represented
by mol percentage based on the following oxides, 26% to 43% of
B2O3, 30% to 37% of ZnO, 17% to 23% of Bi2O3, 2% to
21% of SiO2, and 0 to 2% of P2O5, and a total amount of
B2O3-content and ZnO-content is 78% or less.

Claims:

1. Glass for a scattering layer of an organic LED element, comprising: as
represented by mol percentage based on the following oxides, 26% to 43%
of B2O3, 30% to 37% of ZnO, 17% to 23% of Bi2O3, 2%
to 21% of SiO2, and 0 to 2% of P2O5; and a total amount of
B2O3-content and ZnO-content is 78% or less.

2. The glass for the scattering layer of the organic LED element as
claimed in claim 1, which includes substantially no alkaline metal oxides
(Li2O, Na2O, and K2O), lead (PbO, Pb3O4), nor
P2O5, except for being included as an impurity.

3. A method of manufacturing a laminated substrate for an organic LED
element having a translucent substrate and a scattering layer, wherein:
the scattering layer includes, within a base material made of glass, a
scattering material having a refractive index different from that of the
glass and dispersed within the base material, and is formed by sintering
a raw material including the glass; and the glass includes, as
represented by mol percentage based on the following oxides, 26% to 43%
of B2O3, 30% to 37% of ZnO, 17% to 23% of Bi2O3, 2%
to 21% of SiO2, and 0 to 2% of P2O5, and a total amount of
B2O3-content and ZnO-content is 78% or less.

4. The method of manufacturing the laminated substrate of the organic LED
element as claimed in claim 3, wherein the glass includes substantially
no alkaline metal oxides (Li2O, Na2O, and K2O), lead (PbO,
Pb3O4), nor P2O5, except for being included as an
impurity.

5. The method of manufacturing the laminated substrate of the organic LED
element as claimed in claim 3, wherein the scattering layer is formed by
sintering the raw material at a temperature higher than or equal to a
glass-transition temperature of the glass plus 100.degree. C.

6. The method of manufacturing the laminated substrate of the organic LED
element as claimed in claim 3, wherein the scattering material includes
ceramic particles.

7. The method of manufacturing the laminated substrate of the organic LED
element as claimed in claim 6, wherein an average particle diameter of
the ceramic particles is 1 μm or less.

8. The method of manufacturing the laminated substrate of the organic LED
element as claimed in claim 6, wherein a ratio of the ceramic particles
occupying the scattering layer is 5 volume % or less.

9. A laminated substrate for an organic LED element having a translucent
substrate and a scattering layer, wherein: the scattering layer includes,
within a base material made of glass, a scattering material having a
refractive index different from that of the glass and dispersed within
the base material; and the glass includes, as represented by mol
percentage based on the following oxides, 26% to 43% of B2O3,
30% to 37% of ZnO, 17% to 23% of Bi2O3, 2% to 21% of SiO2,
and 0 to 2% of P2O5, and a total amount of
B2O3-content and ZnO-content is 78% or less.

10. A method of manufacturing an organic LED element having a translucent
substrate, a scattering layer, a first electrode, an organic layer, and a
second electrode in this order, wherein: the scattering layer includes,
within a base material made of glass, a scattering material having a
refractive index different from that of the glass and dispersed within
the base material, and is formed by sintering a raw material including
the glass; and the glass includes, as represented by mol percentage based
on the following oxides, 26% to 43% of B2O3, 30% to 37% of ZnO,
17% to 23% of Bi2O3, 2% to 21% of SiO2, and 0 to 2% of
P2O5, and a total amount of B2O3-content and
ZnO-content is 78% or less.

11. The method of manufacturing the organic LED element as claimed in
claim 10, wherein the glass includes substantially no alkaline metal
oxides (Li2O, Na2O, and K2O), lead (PbO, Pb3O4),
nor P2O5, except for being included as an impurity.

12. The method of manufacturing the organic LED element as claimed in
claim 10, wherein the scattering layer is formed by sintering the raw
material at a temperature higher than or equal to a glass-transition
temperature of the glass plus 100.degree. C.

13. The method of manufacturing the organic LED element as claimed in
claim 10, wherein the scattering layer includes ceramic particles.

14. The method of manufacturing the organic LED element as claimed in
claim 13, wherein an average particle diameter of the ceramic particles
is 1 μm or less.

15. The method of manufacturing the organic LED element as claimed in
claim 13, wherein a ratio of the ceramic particles occupying the
scattering layer is 10 volume % or less.

16. An organic LED element comprising: a translucent substrate, a
scattering layer, a first electrode, an organic layer, and a second
electrode in this order, wherein the scattering layer includes, within a
base material made of glass, a scattering material having a refractive
index different from that of the glass and dispersed within the base
material; and wherein the glass includes, as represented by mol
percentage based on the following oxides, 26% to 43% of B2O3,
30% to 37% of ZnO, 17% to 23% of Bi2O3, 2% to 21% of SiO2,
and 0 to 2% of P2O5, and a total amount of
B2O3-content and ZnO-content is 78% or less.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation application filed under 35
U.S.C. 111(a) claiming the benefit under 35 U.S.C. 120 and 365(c) of a
PCT International Application No. PCT/JP2012/076238 filed on Oct. 10,
2012 and designated the U.S., which is based upon and claims the benefit
of priority of Japanese Patent Application No. 2011-226947 filed on Oct.
14, 2011, the entire contents of which are incorporated herein by
reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to glass for a scattering layer of an
organic LED element, a laminated substrate for the organic LED element
and a method of manufacturing the same, and an organic LED element and a
method of manufacturing the same.

[0004] 2. Description of the Related Art

[0005] Conventionally, it is known to provide a scattering layer within an
organic LED element in order to improve a light extraction efficiency of
the organic LED element (for example, refer to International Publication
No. 2011/046156). The scattering layer includes a scattering material
dispersed within a base material that is made of glass. This scattering
layer is formed by coating glass powder (glass frits) on a translucent
substrate and sintering the glass powder.

[0006] In a case in which the glass uneasily flows when sintering the
glass frits, the surface of the scattering layer becomes rough, and
electrodes formed on the scattering layer may become short-circuited.

[0007] Fluidity of the glass at the time of the sintering is determined by
a sintering temperature, a glass-transition temperature,
crystallizability of glass, and the like. The glass more easily flows as
the sintering temperature becomes higher relative to the glass-transition
temperature.

[0008] However, an upper limit of the sintering temperature is determined
by a heat resistance and the like of the translucent substrate. In
addition, glass having a low glass-transition temperature tends to easily
crystallize at the time of the sintering, and the fluidity of the glass
considerably deteriorates when the crystallization occurs. Hence, it is
difficult to improve the fluidity of the glass at the time of the
sintering by simply lowing the glass-transition temperature. Further, the
surface becomes rough when the crystallization occurs. For this reason,
the surface roughness of the scattering layer has room for improvement.
The Patent Document 1 has no specific disclosure with regard to the above
described problem.

SUMMARY OF THE INVENTION

[0009] The present invention is conceived in view of the above described
problem, and one object is to provide glass for a scattering layer of an
organic LED element, a laminated substrate for the organic LED element
and a method of manufacturing the same, and an organic LED element and a
method of manufacturing the same, in which the surface roughness of the
scattering layer can be reduced.

[0010] In order to achieve the above object, glass for a scattering layer
of an organic LED element in an embodiment (1) of the present invention
includes:

[0011] as represented by mol percentage based on the following oxides, 26%
to 43% of B2O3, 30% to 37% of ZnO, 17% to 23% of
Bi2O3, 2% to 21% of SiO2, and 0 to 2% of P2O5;
and

[0012] a total amount of B2O3-content and ZnO-content is 78% or
less.

[0013] In a method of manufacturing a laminated substrate for an organic
LED element having a translucent substrate and a scattering layer in an
embodiment (2) of the present invention,

[0014] the scattering layer includes, within a base material made of
glass, a scattering material having a refractive index different from
that of the glass and dispersed within the base material, and is formed
by sintering a raw material including the glass; and

[0015] the glass includes, as represented by mol percentage based on the
following oxides, 26% to 43% of B2O3, 30% to 37% of ZnO, 17% to
23% of Bi2O3, 2% to 21% of SiO2, and 0 to 2% of
P2O5, and a total amount of B2O3-content and
ZnO-content is 78% or less.

[0016] In a laminated substrate for an organic LED element having a
translucent substrate and a scattering layer in an embodiment (3) of the
present invention,

[0017] the scattering layer includes, within a base material made of
glass, a scattering material having a refractive index different from
that of the glass and dispersed within the base material; and

[0018] the glass includes, as represented by mol percentage based on the
following oxides, 26% to 43% of B2O3, 30% to 37% of ZnO, 17% to
23% of Bi2O3, 2% to 21% of SiO2, and 0 to 2% of
P2O5, and a total amount of B2O3-content and
ZnO-content is 78% or less.

[0019] In a method of manufacturing an organic LED element having a
translucent substrate, a scattering layer, a first electrode, an organic
layer, and a second electrode in this order in an embodiment (4) of the
present invention,

[0020] the scattering layer includes, within a base material made of
glass, a scattering material having a refractive index different from
that of the glass and dispersed within the base material, and is formed
by sintering a raw material including the glass; and

[0021] the glass includes, as represented by mol percentage based on the
following oxides, 26% to 43% of B2O3, 30% to 37% of ZnO, 17% to
23% of Bi2O3, 2% to 21% of SiO2, and 0 to 2% of
P2O5, and a total amount of B2O3-content and
ZnO-content is 78% or less.

[0022] In an organic LED element having a translucent substrate, a
scattering layer, a first electrode, an organic layer, and a second
electrode in this order in an embodiment (5) of the present invention,

[0023] the scattering layer includes, within a base material made of
glass, a scattering material having a refractive index different from
that of the glass and dispersed within the base material; and

[0024] the glass includes, as represented by mol percentage based on the
following oxides, 26% to 43% of B2O3, 30% to 37% of ZnO, 17% to
23% of Bi2O3, 2% to 21% of SiO2, and 0 to 2% of
P2O5, and a total amount of B2O3-content and
ZnO-content is 78% or less.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 is a cross sectional view illustrating an organic LED
element in an embodiment of the present invention.

MODE OF CARRYING OUT THE INVENTION

[0026] A description will hereinafter be given of embodiments of the
present invention with reference to the drawings. The following
embodiments are examples, and various variations and modifications may be
made without departing from the object of the present invention.

[0027] FIG. 1 is a cross sectional view illustrating an organic LED
element in an embodiment of the present invention.

[0028] As illustrated in FIG. 1, the organic LED element is a bottom
emission type organic LED, for example, and includes a translucent
substrate 110, a scattering layer 120, a first electrode 130, an organic
layer 140, and a second electrode 150 in this order. The first electrode
130 is an anode to supply holes to the organic layer 140, and may be a
transparent electrode that transmits light emitted from the organic layer
140 towards the scattering layer 120. The second electrode 150 is a
cathode to supply electrons to the organic layer 140, and may be a
reflecting electrode that reflects the light emitted from the organic
layer 140 towards the organic layer 140.

[0029] In this embodiment, the first electrode 130 is the anode and the
second electrode 150 is the cathode, however, the first electrode 130 may
be the cathode and the second electrode 150 may be the anode.

[0030] (Translucent Substrate)

[0031] The translucent substrate 110 is made of a material having a high
transmittance with respect to visible light. For example, the translucent
substrate 110 may be a glass substrate or a plastic substrate, however,
because the plastic substrate may become deformed at the time of
sintering the glass frits, it is preferable to use the glass substrate.

[0032] The glass used for the glass substrate may be alkali glass,
borosilicate glass, fused silica, and the like. Generally, alkali
silicate glass such as soda-lime glass is used. A general alkali silicate
glass substrate has an average linear thermal expansion coefficient at
50° C. to 300° C. (hereinafter simply referred to as
"average linear thermal expansion coefficient") of approximately
83×10-7/° C., and an annealing temperature of
approximately 550° C. to approximately 630° C. Because the
glass substrate may become deformed when subjected to a heat treatment at
a temperature higher than or equal to the annealing temperature, it is
preferable to form the scattering layer 120 at a temperature lower than
the annealing temperature.

[0033] The plastic substrate has a low moisture resistance compared to the
glass substrate, and may thus be configured to include a barrier. For
example, a glass layer may be formed on a surface of the plastic
substrate, opposite to the surface provided with the scattering layer
120.

[0034] The translucent substrate 110 has a thickness of 0.1 mm to 2.0 mm,
for example.

[0035] The scattering layer 120 is formed on the translucent substrate
110, and a laminated substrate is formed by the translucent substrate
110, the scattering layer 120, and the like. A scattering layer forming
surface of the glass substrate forming the translucent substrate 110 may
be subjected to a surface treatment such as silica coating and the like.
In other words, a protection layer formed by a silica layer and the like
may be formed between the glass substrate forming the translucent
substrate 110 and the scattering layer 120. Details of the scattering
layer 120 will be described later. The first electrode 130 is formed on
the scattering layer 120.

[0036] (First Electrode)

[0037] The first electrode 130 is the anode to supply the holes to the
organic layer 140, and forms the transparent electrode that transmits the
light emitted from the organic layer 140 towards the scattering layer
120. The first electrode 130 is formed by a material having a high work
function and a high transmittance (for example, a transmittance of 80% or
higher).

[0039] The first electrode 130 has a thickness of 50 nm or greater, for
example. The electrical resistance becomes high when the thickness of the
first electrode 130 is less than 50 nm.

[0040] The first electrode 130 has a refractive index of 1.7 to 2.2, for
example. A carrier concentration of ITO may be increased in order to
reduce the refractive index of the ITO forming the first electrode 130.
The higher the Sn concentration of ITO, the lower the refractive index of
the ITO. However, as the Sn concentration increases, mobility and
transmittance decrease, and the Sn concentration is set to balance the
mobility and transmittance.

[0041] In this specification, "refractive index" refers to the refractive
index that is measured at 25° C. using d-line (wavelength: 587.6
nm) of a He lamp, unless otherwise indicated.

[0042] The first electrode 130 may be made up of a single layer or made up
of a plurality of layers. In addition, an auxiliary wiring may be formed
to make contact with the first electrode 130 at a part above the first
electrode or at a part under the first electrode 130. Materials used for
the auxiliary wiring may include metals such as Au, Ag, Cu, Al, Cr, Mo,
Pt, W, Ni, Ru, and the like, metal compounds, and the like.

[0043] The organic layer 140 is formed on the first electrode 130.

[0044] (Organic Layer)

[0045] The organic layer 140 may have a general configuration including at
least an emissive layer, and may include a hole injecting layer, a hole
transport layer, an electron transport layer, and an electron injecting
layer if necessary. For example, the organic layer 140 includes, from the
anode side, the hole injecting layer, the hole transport layer, the
emissive layer, the electron transport layer, and the electron injecting
layer in this order.

[0046] The hole injecting layer is formed by a material having a small
ionization potential difference with respect to the anode. Polyethylene
dioxythiophene (PEDOT:PSS) and the like, doped with polystyrene sulfonic
acid (PSS), are used as the high-molecular-weight material.
Phthalocyanenes such as copper phthalocyanene (CuPc) and the like are
used as the low-molecular-weight material.

[0047] The hole transport layer transports the holes injected from the
hole injecting layer to the emissive layer. Materials used for the hole
transport layer include a triphenylamine derivative,
N,N'-Bis(1-naphthyl)-N,N'-Diphenyl-1,1'-biphenyl-4,4'-diamine (NPD),
N,N'-Diphenyl-N,N'-Bis[N-phenyl-N-(2-naphtyl)-4'-aminobiphenyl-4-yl]-1,1'-
-biphenyl-4,4'-diamine (NPTE),
1,1'-bis[(di-4-tolylamino)phenyl]cyclohexane (HTM2), and
N,N'-Diphenyl-N,N'-Bis(3-methylphenyl)-1,1'-diphenyl-4,4'-diamine (TPD),
and the like, for example. The hole transport layer preferably has a
thickness of 10 nm to 150 nm. The thinner the hole transport layer, the
lower the voltage, however, the thickness of the hole transport layer is
preferably 10 nm to 150 nm in view of the problem of the electrodes that
may become short-circuited.

[0048] The emissive layer emits light using energy that is generated by
recombination of the holes and the electrons injected from the anode and
the cathode. Doping of emissive dye to a host material forming the
emissive layer enables a high emission efficiency to be obtained, and
also converts an emission wavelength. Organic materials used for the
emission layer include low-molecular weight materials and
high-molecular-weight materials. In addition, the organic materials are
categorized into fluorescent materials and phosphorescent materials
depending on the emission mechanism. The organic materials forming the
emissive layer include, for example, a metal complex of quinoline
derivative, such as tris(8-quinolinolate) aluminum complex (Alq3),
bis(8-hydroxy) quinaldine aluminum phenoxide (Alq'2OPh), bis(8-hydroxy)
quinaldine aluminum-2,5-dimethylphenoxide (BAlq),
mono(2,2,6,6-tetramethyl-3,5-heptanedionate)lithium complex (Liq),
mono(8-quinolinolate)sodium complex (Naq),
mono(2,2,6,6-tetramethyl-3,5-heptanedionate) lithium complex,
mono(2,2,6,6-tetramethyl-3,5-heptanedionate) sodium complex,
bis(8-quinolinolate) calcium complex (Caq2), and the like, or a
fluorescent substance, such as tetraphenylbutadiene, phenylquinacridone
(QD), anthracene, perylene, coronene, and the like. The host material is
preferably a quinolinolate complex, and an aluminum complex having
8-quinolinol and a derivative thereof as a ligand is particular
preferable.

[0049] The electron transport layer transports the electrons injected from
the electrode. Materials used for the electron transport layer include,
for example, a quinolinol aluminum complex (Alq3), an oxadiazole
derivative (for example, 2,5-bis(1-naphthyl)-1,3,4-oxadiazole (END),
2-(4-t-butylphenyl)-5-(4-biphenyl)-1,3,4-oxadiazole (PBD) and the like),
a triazole derivative, a bathophenanthroline derivative, a silole
derivative, and the like.

[0050] The electron injecting layer may be a layer doped with an alkali
metal such as lithium (Li), cesium (Cs), and the like to the cathode
surface, for example.

[0051] The second electrode 150 is formed on the organic layer 140.

[0052] (Second Electrode)

[0053] The second electrode 150 is the cathode to supply the electrons to
the organic layer 140, and forms the reflecting electrode that reflects
the light emitted from the organic layer 140 towards the organic layer
140. The second electrode 150 is formed by a metal having a small work
function, or an alloy of such a metal.

[0054] Materials used for the second electrode 150 include alkali metals,
alkaline earth metals, metals in group 3 of the periodic table, and the
like, for example. Aluminum (Al), magnesium (Mg), silver (Ag), alloys of
such metals, and the like may be used for such materials.

[0055] For example, the second electrode 150 may be a codeposited layer of
MgAg, a laminated electrode having Al deposited on a thin film deposition
of LiF or Li2O, or an electrode having aluminum (Al) stacked on a
layer of alkaline earth metal (for example, Ca or Ba).

[0056] (Scattering Layer)

[0057] The scattering layer 120 is provided between the translucent
substrate 110 and the first electrode 130. Generally, the refractive
index of the translucent substrate 110 is lower than the refractive index
of the first electrode 130, and in a state in which no scattering layer
120 is provided, total reflection occurs and there exists a large portion
of the light that cannot be extracted to the outside. The scattering
layer 120 changes propagating directions of such light by scattering, in
order to increase the light extraction efficiency with which the light
can be extracted to the outside.

[0058] As illustrated in FIG. 1, the scattering layer 120 includes a
scattering material 122 having a refractive index different from that of
glass, dispersed within a base material 121 made of glass. The scattering
layer 120 is formed by sintering a raw material (for example, paste)
including the glass. The raw material may include the scattering material
122. In a case in which the scattering material 122 is a gas such as air,
the gas need not be included in the raw material, and the gas may be
introduced into the glass at the time of the sintering.

[0059] The refractive index of the base material 121 at a predetermined
wavelength is preferably higher than or equal to the refractive index of
the first electrode 130. In this case, the light extraction efficiency
with which the light is extracted to the outside is improved, because
total reflection of light having the predetermined wavelength does not
occur at an interface between the first electrode 130 and the scattering
layer 120. The predetermined wavelength may be at least a part (for
example, red, blue, or green) of a wavelength range of the light emitted
from the organic layer 140, and is preferably the entire region (430 nm
to 650 nm) of the wavelength range of the emitted light, and more
preferably the entire region (360 nm to 830 nm) of the wavelength range
of visible light.

[0060] A difference between the refractive index of the base material 121
and the refractive index of the scattering material 122 is preferably
0.05 or greater at the predetermined wavelength described above.

[0061] A surface roughness Ra of the scattering layer 120 is preferably
100 nm or less, more preferably 90 nm or less, and further preferably 80
nm or less. When the surface roughness Ra of the scattering layer 120
exceeds 100 nm, the short-circuiting of the first electrode 130 and the
second electrode 150 formed on the surface of the scattering layer 120
may occur, and a leak current may be generated. The surface roughness Ra
is a microscopically observed surface roughness having a value that is
obtained by eliminating a long-wavelength component by setting a cutoff
value λc of a profile filter prescribed by JIS B 0601-2001 to 2.5
mm, and can be measured by an atomic force microscope (AFM) and the like,
for example.

[0062] (Scattering Material)

[0063] The scattering material 122 has a refractive index different from
that of the base material 121. Ceramic particles having low reaction with
the base material 121, and shapes, dimensions, and contents thereof that
are easily controllable, are used for the scattering material 122. The
ceramic particles may be formed by silica (SiO2), alumina
(Al2O3), titania (TiO2), zirconia (ZrO2), and the
like, for example. A plurality of kinds of ceramic particles may be used.
Zirconia (ZrO2) has a particularly good wettability with respect to
the base material 121 at the time of the sintering, and can easily form a
smooth surface, and thus, it is particularly preferable to use zirconia
(ZrO2) as the scattering material 122.

[0064] Besides the ceramic particles, glass having a composition different
from that of the glass used for the base material 121, or a gas such as
air and the like, may be used for the scattering material 122. The gas
may be included in the scattering layer 120 in the form of bubbles.

[0065] A ratio of the scattering material 122 occupying the scattering
layer 120 is appropriately set depending on the kind of the scattering
material 122 used. In the case in which the ceramic particles are used
for the scattering material 122, the ratio described above is preferably
1 volume % to 10 volume %. When the ratio described above is less than 1
volume %, sufficient scattering cannot be obtained in order to extract
the light from the organic LED. On the other hand, when the ratio
described above exceeds 10 volume %, the ceramic particles project from
the surface of the sintered layer, and there is a possibility of
increasing the short-circuit or the leak current of the organic LED.

[0066] In a case in which a plurality of kinds of scattering materials 122
are dispersed within the scattering layer 120, "the ratio of the
scattering material 122 occupying the scattering layer 120" refers to a
total of the ratios of all of the scattering materials 122.

[0067] The dimensions and shapes of the scattering material 122 are
appropriately set depending on the kind of the scattering material 122.
An average particle diameter (D50) of the ceramic particles used for the
scattering material 122 is preferably 0.05 μm to 1 μm. When D50 is
less than 0.05 μm, sufficient scattering cannot be obtained in order
to extract the light from the organic LED, and because a wavelength
dependency of the scattering intensity increases to make it difficult to
control the scattering intensity, it becomes difficult to control the
tone of color of the light that is extracted. On the other hand, when D50
is greater than 1 μm, sufficient scattering cannot be obtained in
order to extract the light from the organic LED. D50 is the 50% diameter
prescribed by JIS R 1629-1997.

[0068] In a case in which the ceramic particles are used, the refractive
index of the scattering material 122 is preferably 1.8 or lower, or 2.1
or higher. When the refractive index of the ceramics is higher than 1.8
and lower than 2.1, sufficient extraction of light cannot be expected.

[0069] (Base Material)

[0070] The glass (hereinafter referred to as "base material glass")
forming the base material 121 is manufactured by mixing a plurality of
kinds of glass raw materials at predetermined ratios, heating and melting
the mixture, and thereafter cooling the mixture. The base material glass
that is manufactured is broken into pieces by a mill, and classified if
necessary, in order to obtain glass in powder form (glass frits). The
glass frits are sintered in order to form the base material 121.

[0071] The base material glass preferably includes, as represented by mol
percentage based on the following oxides, 26% to 43% and preferably 36%
to 43% of B2O3, 30% to 37% of ZnO, 17% to 23% of
Bi2O3, 2% to 21% and preferably 2% to 11% of SiO2, and 0
to 2% of P2O5, and a total amount of the B2O3-content
and the ZnO-content is 78% or less.

[0072] According to the glass composition described above, the average
linear thermal expansion coefficient is small (difference from the
average linear thermal expansion coefficient of an alkali silicate glass
substrate is small), the refractive index is high, the glass-transition
temperature is low, and the crystallization of glass at the time of
sintering the glass frits can be suppressed. Because the glass-transition
temperature is low and the crystal deposition can be suppressed, the
fluidity of glass at the time of sintering the glass frits can be
improved, and the surface roughness of the scattering layer 120 can be
reduced. Each component will be described in the following. In the
description of each component, "%" refers to mol %.

[0073] B2O3 is a component that forms the framework of the
glass. The B2O3-content of the base material glass is 26% to
43%, and preferably 36% to 43%. When the B2O3-content of the
base material glass is less than 26%, devitrification of the glass easily
occurs at the time of the manufacture, and in addition, the glass easily
crystallizes at the time of sintering the glass frits. On the other hand,
when the B2O3-content of the base material glass exceeds 43%,
the glass-transition temperature becomes high. In addition, when the
B2O3-content of the base material glass exceeds 43%, the
refractive index decreases and is thus not preferable.

[0074] ZnO is a component that stabilizes the glass. The ZnO-content of
the base material glass is 30% to 37%. When the ZnO-content of the base
material glass is less than 30%, the glass-transition temperature becomes
high, and the linear thermal expansion coefficient becomes large. On the
other hand, when ZnO-content of the base material glass exceeds 37%,
devitrification of the glass easily occurs at the time of the
manufacture, and in addition, the glass easily crystallizes at the time
of sintering the glass frits. In addition, when ZnO-content of the base
material glass exceeds 37%, the weather resistance of the glass may
deteriorate.

[0075] A total amount of the B2O3-content and the ZnO-content of
the base material glass is 78% or less. When the total amount of the
B2O3-content and the ZnO-content of the base material glass
exceeds 78%, the glass easily crystallizes at the time of sintering the
glass frits.

[0076] Bi2O3 is a component that increases the refractive index
and lowers the glass-transition temperature. The Bi2O3-content
of the base material glass is 17% to 23%. When the
Bi2O3-content of the base material glass is less than 17%, the
refractive index becomes low, and the glass-transition temperature
becomes high. On the other hand, when the Bi2O3-content of the
base material glass exceeds 23%, the average linear thermal expansion
coefficient becomes large, and the glass easily crystallizes at the time
of sintering the glass frits.

[0077] SiO2 is a component that increases the stability of the glass
and suppresses the crystallization at the time of sintering the glass
frits. The SiO2-content of the base material glass is 2% to 21%, and
preferably 2% to 11%. When the SiO2-content of the base material
glass is less than 2%, the glass easily crystallizes at the time of
sintering the glass frits. On the other hand, when the SiO2-content
of the base material glass exceeds 21%, the dissolving temperature of the
glass raw material becomes high, and deterioration and the like of a
melter occurs, to thereby make it difficult to manufacture the glass.

[0078] P2O5 is an arbitrary component that suppresses
crystallization at the time of sintering the glass frits. The
P2O2-content of the base material glass is 0 to 2%. When the
P2O2-content of the base material glass exceeds 2%, the
glass-transition temperature becomes high, and the average linear thermal
expansion coefficient becomes large. In addition, when the
P2O2-content of the base material glass exceeds 2%, the
refractive index decreases. Because the effect of P2O2 on the
glass-transition temperature is large, it is preferable to include
substantially no P2O2 except for cases in which P2O2
is included as an impurity.

[0079] Al2O3 is an arbitrary component that increases the
stability of glass. The Al2O3-content of the base material
glass is preferably 0 to 7%. When the Al2O3-content of the base
material glass exceeds 7%, devitrification of the glass easily occurs at
the time of the manufacture, and in addition, the glass easily
crystallizes at the time of sintering the glass frits.

[0080] ZrO2 is an arbitrary component that suppresses crystallization
at the time of sintering the glass frits. The ZrO2-content of the
base material glass is preferably 0 to 7%. When the ZrO2-content of
the base material glass exceeds 7%, devitrification of the glass easily
occurs at the time of the manufacture, and the glass-transition
temperature may become high.

[0081] Gd2O3 is an arbitrary component that increases the
refractive index while suppressing the average linear thermal expansion
coefficient to a low value, and also suppresses crystallization at the
time of sintering the glass frits. The Gd2O3-content of the
base material glass is preferably 0 to 5%. When the
Gd2O3-content of the base material glass exceeds 5%,
crystallization of the glass may easily occur at the time of sintering
the glass frits.

[0082] TiO2 is a component that is not essential but increases the
refractive index of the base material glass, and the TiO2-content of
the base material glass may be up to 5%. However, when the base material
glass includes an excessive amount of TiO2, crystallization of the
glass may easily occur at the time of sintering the glass frits.

[0083] WO3 is a component that is not essential but increases the
refractive index of the base material glass, and the WO3-content of
the base material glass may be up to 5%. However, when the base material
glass includes an excessive amount of WO3, crystallization of the
glass may easily occur at the time of sintering the glass frits.

[0084] Alkaline earth metal oxides (MgO, CaO, SrO, and BaO) are arbitrary
components that decrease the glass-transition temperature. The content of
the alkaline earth metal oxides in the base material glass is preferably
0 to 5%. When the content of the alkaline earth metal oxides in the base
material glass exceeds 5%, the average linear thermal expansion
coefficient becomes large, and crystallization of the glass may easily
occur at the time of sintering the glass frits.

[0085] Substantially no Li2O, Na2O, and K2O are included in
the base material glass, except for cases in which Li2O, Na2O,
and K2O are included as impurities. When these alkaline metal oxides
are included in the base material glass, alkali metal ions may scatter
during a heat treatment process. The alkali metal ions may cause
undesirable effects on the electrical operation of the organic LED
element.

[0086] Substantially no PbO and Pb3O4 are included in the base
material glass, except for cases in which PbO and Pb3O4 are
included as impurities. Hence, it is possible to satisfy the needs of the
user who wishes to avoid the use of lead.

[0087] The base material glass may include, within a range in which the
effects of the embodiment are obtainable, GeO2, Nb2O5,
Y2O3, Ce2O3, O2, La2O3, TeO2,
SnO, SnO2, Sb2O3, Ta2O5, and the like, for
example, which amount to a total of 5% or less. In addition, the base
material glass may include a small amount of coloring agent in order to
adjust the tone of color. Known coloring agents, such as transition metal
oxides, rare earth metal oxides, metal colloids, and the like, may be
used as the coloring agent. These coloring agents may be used
independently or in combination.

[0088] A refractive index nd of the base material glass is preferably
1.80 or higher, more preferably 1.85 or higher, and further preferably
1.90 or higher. When the refractive index nd is lower than 1.8, the
effect of the total reflection at the interface between the scattering
layer 120 and the first electrode 130 is large, and the light extraction
efficiency may easily deteriorate.

[0089] A glass transition temperature Tg of the base material glass is
preferably 475° C. or lower, more preferably 470° C. or
lower, and further preferably 465° C. or lower. When the glass
transition temperature Tg is 475° C. or lower, the glass may
easily flow at the time of sintering the glass frits in a case in which
the sintering of the glass frits is performed at a temperature lower than
or equal to the annealing temperature of the general glass substrate. In
addition, the glass has a good wettability with respect to the ceramic
particles of the scattering material 122 at the time of sintering the
glass frits, and a good surface roughness of the scattering layer 120 can
be obtained.

[0090] An average linear thermal expansion coefficient α of the base
material glass is preferably 60×10-7/° C. to
100×10-7/° C., and more preferably
70×10-7/° C. to 90×10-7/° C. When the
average linear thermal expansion coefficient α is within a range of
60×10-7/° C. to 100×10-7/° C., a
difference (absolute value) from the average linear thermal expansion
coefficient of the alkali silicate glass substrate forming the
translucent substrate 110 is small, and damage and warp to the substrate
with respect to temperature changes can be reduced.

[0091] (Method of Manufacturing Scattering Layer)

[0092] The scattering layer 120 is formed by coating the raw material (for
example, paste) including the glass frits on the translucent substrate
110 and sintering this raw material. The raw material may include the
scattering material 122. In a case in which the scattering material 122
is a gas such as air, the gas need not be included in the raw material,
and the gas may be introduced into the glass at the time of the
sintering.

[0093] (1) Glass Frits

[0094] The glass frits are powders of the base material glass. D50 of the
base material glass powder is preferably 1 μm to 10 μm from the
standpoint of coating ease. Surface modification of the base material
glass powder may be made using a surfactant or a silane coupling agent.

[0095] (2) Paste

[0096] The paste is made by mixing the ceramic particles of the scattering
material 122 and vehicle, in addition to the glass frits. The coating
ease onto the translucent substrate 110 is improved by mixing the
vehicle. In a case in which the scattering material 122 is formed by a
gas, the glass frits and the vehicle are mixed to make the paste. The
paste does not need to include air bubbles, because the air bubbles may
be formed at the time of sintering the paste.

[0097] The paste is obtained by mixing the glass frits, the ceramic
particles, and the vehicle in a planetary mixer and the like, and
uniformly dispersing the paste by a triple roll mill and the like. A
solvent and the like may be added and further mixed in the mixer, in
order to adjust the viscosity. The paste is obtained by mixing a total of
70 mass % to 80 mass % of the glass frits and the ceramic particles to 20
mass % to 30 mass % of the vehicle, at this proportion.

[0098] The vehicle is a mixture of a resin and a solvent, and further
mixed with a surfactant. The vehicle is obtained by mixing the resin, the
surfactant, and the like to the solvent that is heated to 50° C.
to 80° C., for example, and filtering the mixture after resting
the mixture for 4 hours to 12 hours.

[0099] The resin retains the shape of a coating layer of the paste.
Examples of the resin include ethyl cellulose, nitrocellulose, acrylic
resin, vinyl acetate, butyral resin, melamine resin, alkyd resin, rosin
resin, and the like. Ethyl cellulose, nitrocellulose, and the like may be
used as a base resin. The strength of the coating layer may be improved
by adding butyral resin, melamine resin, alkyd resin, or rosin resin.

[0100] The solvent has a function to dissolve the resin and to adjust the
viscosity. The solvent preferably does not dry during the coating and
dries quickly during the drying, and preferably has a boiling temperature
of 200° C. to 230° C. Examples of the solvent include an
ether type solvent (butyl carbitol (BC), butyl carbitol acetate (BCA),
diethylene glycol di-n-butyl ether, dipropylene glycol butyl ether,
tripropylene glycol butyl ether, butyl cellosolve acetate, an alcohol
type solvent (α-terpineol, pine oil, Dowanol), an ester type
solvent (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate), a phthalic
acid ester type solvent (DBP (dibutyl phthalate), DMP (dimethyl
phthalate), DOP (dioctyl phthalate)), and the like. These solvents may be
used independently or in combination in order to adjust the viscosity,
the content ratio, and the drying speed. Generally, α-terpineol or
2,2,4-trimethyl-1,3-pentanediol monoisobutyrate is mainly used as the
solvent. Further, DBP (dibutyl phthalate, DMP (dimethyl phthalate), and
DOP (dioctyl phthalate) also function as a plasticizer.

[0101] A method of coating the paste on the translucent substrate 110 uses
screen printing, doctor blade printing, dye-coat printing, and the like.
It is also possible to use a method that creates a green sheet by coating
the paste on a base material that is separate from the translucent
substrate 110 and drying the paste, and separating the green sheet from
the base material and bonding the green sheet on the translucent
substrate 110 by thermocompression bonding.

[0102] In a case in which the screen printing is used, the thickness of
the coating layer can be controlled by adjusting a mesh size of a screen
stencil, the thickness of an emulsion, a pressing force at the time of
printing, a pushing amount of a squeegee, and the like.

[0103] In a case in which the doctor blade printing or the dye-coat
printing is used, the coating layer can be made thicker compared to the
case in which the screen printing is used.

[0104] The coating layer may be made thicker by repeating the coating and
drying.

[0105] (4) Sintering

[0106] Sintering of the coating layer of the paste includes a decomposing
process to decompose and eliminate the resin within the paste, and a
softening process to soften the glass frits after the decomposing
process. The decomposing process is performed at atmospheric conditions
for 20 minutes to 1 hour, by heating at 350° C. to 400° C.
in the case in which ethyl cellulose is used for the resin, and at
200° C. to 300° C. in the case in which nitrocellulose is
used for the resin. The softening process is preferably performed at
atmospheric conditions for 20 minutes to 1 hour, by heating at a
temperature of the glass-transition temperature Tg+100° C. to the
glass-transition temperature Tg+150° C. By heating at such a
temperature, the fluidity of the glass becomes high, and a part of the
scattering material is unlikely to project from the surface of the glass
layer even when the ceramic particles are used for the scattering
material, to thereby enable a smooth surface to be formed. Even when
heated at such a temperature, the glass-transition temperature Tg is
sufficiently low and the crystallization uneasily occurs, and thus, a
high fluidity of the glass can be obtained when compared to the
conventional case, while suppressing thermal deformation of the
translucent substrate 110 in a manner similar to the conventional case.
By cooling to room temperature after the sintering, the scattering layer
120 is formed on the translucent substrate 110. In a case in which the
fluidity of the glass is to be further increased at the softening
process, the softening process is preferably performed at a temperature
of the glass-transition temperature Tg+130° C. to the
glass-transition temperature Tg+150° C.

EMBODIMENTS

[0107] The present invention is specifically described in the following in
conjunction with examples of embodiments, however, the present invention
is not limited to the following examples of embodiments.

[0108] (Experiment 1)

[0109] In Example 1 through Example 31, molten glass is created to obtain
glass having compositions illustrated in Table 1 through Table 5, by
combining glass raw materials such as B2O3, ZnO,
Bi2O3, SiO2, Al2O3, ZrO2, and the like, in
a platinum melting pot, and heating at 1200° C. for 1.5 hours. The
glass raw material includes substantially no alkaline metal oxides
(Li2O, Na2O, and K2O), lead (PbO, Pb3O4), nor
P2O5. Example 1 through Example 23 and Example 26 through
Example 31 are embodiments, and Example 24 and Example 25 are comparison
examples.

[0110] A part of the molten glass is poured into a carbon mold to create
bulk glass. In order to remove distortions, the bulk glass is heated at
490° C. for 1 hour using an electric furnace, and thereafter
annealed to room temperature using 5 hours. Samples for measuring the
refractive index, and samples (cylindrical column having a diameter of 5
mm and a length of 200 mm) for measuring the glass-transition temperature
and the average linear thermal expansion coefficient are created from the
glass after the annealing.

[0111] The refractive index nd is measured using a refractometer
(KPR-2000 manufactured by Kalnew) using the V-block method. The
refractive index nd is measured at 25° C. using the d-line
(wavelength: 587.6 nm) of the He lamp.

[0112] The glass-transition temperature Tg (° C.) and the average
linear thermal expansion coefficient α (10-7/° C.) are
measured using a thermal expansion meter (TD5000SA manufactured by Bruker
AXS). The temperature raising speed is 5° C./rain. The average
linear thermal expansion coefficient α is the average linear
thermal expansion coefficient at 50° C. to 300° C.

[0113] The remaining part of the molten glass is poured between a pair of
rolls and quenched, to create flake-shaped glass. The flake-shaped glass
is broken into pieces by dry milling of a planetary ball mill for 2
hours, and particles having a particle diameter of 0.6 μm or less and
particles having a particle diameter of 5.0 μm or greater are both
removed using an elbow-jet classifier. The average particle diameter
(D50) of the glass powder obtained is 1.5 μm when measured using a
laser diffraction type particle size distribution measuring apparatus
(SALD-2100 manufactured by Simadzu Corporation).

[0114] The existence of crystals at the surface of the sintered layer is
observed and evaluated by coating and sintering the glass frits on the
alkali silicate glass substrate (PD200 manufactured by Asahi Glass
Company, Limited at an annealing temperature of 620° C.) to form
the glass layer, and observing and evaluating the surface of the glass
layer using an optical microscope. First, the paste is created by mixing
75 g of glass frits and 25 g of organic vehicle (10 mass % of ethyl
cellulose dissolved into α-terpineol). Next, the paste is
screen-printed in a range of 35 mm×35 mm on the alkali silicate
glass substrate (PD200 manufactured by Asahi Glass Company, Limited)
having a size of 100 mm×100 mm and a thickness of 1.8 mm, dried for
30 minutes at 150° C., once returned to room temperature and then
raised to a temperature of 475° C. in 48 minutes, and held at
475° C. for 30 minutes, in order to decompose and eliminate the
resin of the organic vehicle. Thereafter, the temperature is raised to
each glass-transition temperature indicated in Table 1 through Table 4
plus 130° C. (578° C. in Example 1) in 10 minutes, the
temperature is held at the raised temperature (578° C. in Example
1) for 40 minutes to soften the glass, and the temperature is thereafter
lowered to room temperature in 3 hours in order to form the glass layer.
The thickness of the glass layer that is formed is 15 μm. With regard
to the crystals at the surface, "O" indicates the glass layer whose
surface has no crystals recognizable on the optical microscope, and "X"
indicates the glass layer whose surface has crystals recognizable on the
optical microscope. Generally, for the same glass composition, the higher
the sintering temperature the more easily the crystallization occurs. In
addition, generally, for the same glass composition, glass powder having
a particle diameter of several μm more easily crystallizes compared to
glass powder having a particle diameter of several tens of μm.

[0115] The surface roughness Ra of the glass layer is measured using an
atomic force microscope (Surfcorder ET4000A manufactured by Kosaka
Laboratory Ltd.). The cutoff wavelength is set to 2.5 mm to eliminate the
long wavelength component caused by undulation. Measurements are made in
a region at a central part (5 mm×5 mm) on the scattering layer
surface (35 mm×35 mm).

[0117] From Table 1 through Table 5, it is confirmed that the glass in
each of Example 1 through Example 23 and Example 26 through Example 31
has a high refractive index, softening property at low temperatures, and
a low coefficient of thermal expansion. In addition, the glass in each of
Example 1 through Example 23 and Example 26 through Example 31 has the
glass-transition temperature Tg of 475° C. or lower, and no
crystals observed at the surface of the glass layer formed by the
sintered layer, and thus, the surface roughness Ra of the sintered layer
is significantly smaller compared to that of the glass in each of Example
24 and Example 25.

[0118] (Experiment 2)

[0119] In Example 32 through Example 40, the paste is coated and sintered
on the alkali silicate glass substrate to form the scattering layer, in a
manner similar to Example 21, except that a part of the glass frits is
replaced by the ceramic particles illustrated in Table 6 when creating
the paste, and the surface roughness of the scattering layer is
evaluated. In Example 34, the paste is coated and sintered on the alkali
silicate glass substrate to form the scattering layer, in a manner
similar to Example 24, except that a part of the glass frits is replaced
by the ceramic particles illustrated in Table 6 when creating the paste,
and the surface roughness of the scattering layer is evaluated.
Evaluation results are illustrated in Table 7. In Table 7, "Ratio"
indicates a ratio (volume %) of the ceramic particles occupying the
scattering layer. In addition, in Table 7, "Glass A" indicates the glass
having the composition of Example 21, and "Glass B" indicates the glass
having the composition of Example 24. Example 32 through Example 39 are
embodiments, and Example 40 is a comparison example.

[0120] From Table 7, it is confirmed that the scattering layer in each of
Example 32 through Example 39 has a good surface roughness Ra, similar to
that of the sintered layer of Example 21. On the other hand, it is
confirmed that the scattering layer of Example 40 has a large surface
roughness Ra, and is unsuited for forming the organic LED.

[0121] According to the embodiment and examples thereof, glass for a
scattering layer of an organic LED element, a laminated substrate for the
organic LED element and a method of manufacturing the same, and an
organic LED element and a method of manufacturing the same are provided,
in which the surface roughness of the scattering layer can be reduced.

[0122] The embodiment and examples are suited for use in the glass for the
scattering layer of the organic LED element, the laminated substrate for
the organic LED element and the method of manufacturing the same, and the
organic LED element and the method of manufacturing the same.

[0123] Although the examples are numbered with, for example, "1," "2,"
"3," . . . , the ordinal numbers do not imply priorities of the examples.
Many other variations and modifications will be apparent to those skilled
in the art.